Do Geographically Isolated Grasslands Follow the Principle of Island Biogeography in a Landscape Scale? Taking Poyang Lake Grassland as an Example

As one of the basic theories of biodiversity conservation, island biogeography has been widely accepted in the past decades. Originally, island biogeography was put forward and applied in oceanic environments. But later on, it was found out that the application was not only limited to oceanic islands, but also in terrestrial environments with relatively isolated conditions. In terms of biodiversity level, island biogeography generally focuses on a small scale, such as species diversity and genetic diversity. The studies of biodiversity on a large-scale based on island biogeography, such as ecosystem and landscape scales, were seldomly conducted. Taking Poyang Lake, the largest fresh water lake in China as case study area, 30 grasslands were randomly selected to study whether island biogeography can be applied to grasslands at a landscape level from three island attributes (area, distance and shape), and the most important ecological variable (flooding) in Poyang Lake. The results showed that in general, grasslands have the property of an island, and follow the basic principle of island biogeography. We found the area and flooding duration were the two most important determinants of landscape diversity. There was a significant positive correlation between the grassland area and the landscape diversity, which could be well expressed by logarithmic function model (R² = 0.73). There was a negative correlation between flooding duration and landscape diversity, which could be described by an inverse model (R² = 0.206). The distance to mainland and the shape of grassland were correlated with landscape diversity, but the fitting result of the models was not as good as expected. The possible reason could be that Poyang Lake is a seasonal lake, the water level varies with hydrological conditions, so that the grasslands are not strongly isolated and their shape is not stable enough required by island biogeography. Furthermore, it indicates that besides area, distance and shape attributes, flooding strongly affects the biodiversity of grassland vegetation, and should not be ignored when applying island biogeography theory to Poyang Lake. This study is expected to be a supplement for island biogeography in terrestrial environments, and the results are expected to benefit for the biodiversity conservation in Poyang Lake.     

单增李斯特菌胎盘感染的体内外模型研究进展

单核细胞增生李斯特氏菌（Listeria monocytogenes）是重要的食源性致病菌,能引发人类的李斯特菌病,是全球公共卫生问题之一。该菌易感染孕妇,引起胎儿和新生儿的侵袭性李斯特菌病,严重威胁母婴健康。因此,建立有效的单增李斯特菌感染胎盘体内外模型,解析和探究单增李斯特菌经胎盘感染机制,是预防和控制单增李斯特菌感染母婴的关键所在。本文综述了可用于研究单增李斯特菌母婴感染的体内外胎盘模型,总结和讨论了各类模型的优势和局限性;并着重分析了体外三维胎盘屏障模型在单增李斯特菌感染方面的研究进展和未来研究方向。以期为深入解析该菌经胎盘感染的途径、发病机制提供支持,并为预防和控制母婴李斯特菌病提供科学参考。     

非洲猪瘟病毒I226R蛋白抑制cGAS-STING通路介导的天然免疫应答

本研究旨在探究非洲猪瘟病毒(African swine fever virus, ASFV) I226R蛋白(I226R protein, pI226R)抑制cGAS-STING信号通路的作用机制。利用双荧光素酶报告系统和实时荧光定量PCR (real-time quantitative PCR, qPCR)证明pI226R显著抑制cGAS-STING通路介导的I型干扰素及干扰素刺激相关基因的产生。免疫共沉淀及激光共聚焦显微镜试验发现pI226R与cGAS蛋白相互作用。免疫印迹分析证明pI226R通过自噬-溶酶体途径促进cGAS蛋白的降解。同时,pI226R阻碍了cGAS与E3泛素连接酶三基序蛋白56 (tripartite motif protein 56, TRIM56)的结合,导致cGAS的单泛素化减弱,从而抑制了cGAS的活化和cGAS-STING通路的激活。总之,本研究证明ASFV pI226R通过拮抗cGAS进而抑制宿主的抗病毒天然免疫反应,进一步增加了对研究ASFV免疫逃逸机制的理解,为疫苗的研发提供了理论基础。     

儿童最大有氧活动能力的发展特征

本文报告了我国４６３名１０－１９岁儿童青少年的最大有氧活动能力的发展特征。在青春早期,男女童的最大吸氧量绝对值均随年龄增长而增加,男童由１．７５升／分增至３．１０升／分,女童由１．４４升／分增至２．０７升／分,女童增长较少;以后女童即稳定于这一水平,男童仍略有增长。按身高及按最大心率计标的相对值与其有相似的特征。按体重和瘦体重计算的相对值,在男女童都未见随年龄增长的规律。男童ＶＯ２ｍａｘ绝对值及各     

circPVT1通过miR-24-3p/let-7a-5p/FSCN1轴促进鼻咽癌细胞侵袭迁移

目的 鼻咽癌是一种来源于鼻咽上皮的恶性肿瘤,其临床特征之一是易发生淋巴转移,但是目前鼻咽癌转移的分子机制尚未阐明。circPVT1是由PVT1基因2号外显子反向拼接形成的环状RNA (circRNA),在多种肿瘤中表达上调,本文探讨了circPVT1在鼻咽癌侵袭迁移中的作用和分子机制。方法 通过RT-qPCR检测circPVT1及其下游miRNA和FSCN1在鼻咽癌细胞的表达情况,Transwell和划痕愈合实验检测circPVT1对鼻咽癌细胞侵袭迁移的影响,RNA pull-down实验检测circPVT1结合的miRNA,双荧光素酶报告实验检测miR-24-3p和let-7a-5p靶向抑制FSCN1 mRNA表达。结果 在鼻咽癌细胞中过表达circPVT1可以促进鼻咽癌细胞侵袭迁移,而敲低circPVT1则可以抑制鼻咽癌细胞的侵袭迁移。进一步研究发现,circPVT1可以通过竞争性吸附miR-24-3p和let-7a-5p,上调FSCN1的表达,从而促进鼻咽癌细胞的侵袭迁移。结论 circPVT1通过miR-24-3p/let-7a-5p/FSCN1轴促进鼻咽癌细胞侵袭迁移,证实c...     

钾对兰州百合鳞茎中多酚类物质积累代谢及其抗氧化活性的影响

为探究施钾对兰州百合鳞茎中多酚类物质的积累、抗氧化能力及差异代谢物的影响,该研究以兰州百合鳞茎为试材,通过固定氮素(N)和磷素(P)用量,设置不同钾(K)浓度处理,即K_(0)(不施肥)、K_(1)(447.6 mg·L^(-1))、K_(2)(671.4 mg·L^(-1))、K_(3)(895.2 mg·L^(-1)),采用福林-肖卡法、溴甲酚绿比色法、香草醛比色法、DPPH法、铜离子还原能力(CUPRAC)法测定不同K浓度处理下兰州百合鳞茎中多酚类物质含量及其抗氧化活性,并采用LC-MS法分析多酚类物质的差异代谢物,并进行差异代谢物筛选,功能注释及富集分析,为兰州百合的优质栽培提供理论依据。结果表明:(1)不同K浓度处理下兰州百合鳞茎中多酚类物质的含量及其抗氧化活性存在显著差异(P<0.05),与K_(0)相比,K_(1)、K_(2)、K_(3)均能促进鳞茎多酚类物质的积累及其抗氧化能力的提高,其中以K_(2)(671.4 mg·L^(-1))效果最佳。(2)相关性分析表明,兰州百合鳞茎多酚类物质含量与抗氧化活性指标呈极显著(P<0.01)相关关系,相关系数为0.451~0.959。(3)K_(0)、K_(2)浓度处理下兰州百合鳞茎中存在89种多酚类及相关化合物,其中52种相对含量显著上调,37种相对含量显著下调,且显著富集到黄酮类及苯丙类化合物生物合成的通路上。研究认为,兰州百合的最佳施钾量(671.4 mg·L^(-1))能有效促进鳞茎中多酚类物质的积累并提高其抗氧化能力。     

鸡冠花种子蛋白质的提纯及分析

鸡冠花种子干燥后用石油醚脱酯,用凯氏定氮法测定蛋白质含量。按Osbern系统分别提取白蛋白、球蛋白、醇溶蛋白、谷蛋白;用Folin一酚试剂法测定各自相对含量,并用单向和双向SDS—PAGE方法分析种子总蛋白和4类不同溶性蛋白质的组成成分及这些组份的热稳定性。实验发现:鸡冠花种子蛋白质含量达26.04％,白蛋白、球蛋白、醇溶蛋白、谷蛋白的相对含量分别为11.5％、72％、4.6％、12％。SDS—PAGE表明;其种子蛋白中20KD球蛋白成份含量最高,其它一些次要组分为63KD、61KD、15KD、13KD白蛋白成份,58KD、37KD、23KD球蛋白成份,39KD、34KD、25KD谷蛋白成份及26KD醇溶蛋白成份,其中58KD由37KD和20KD两亚基经二硫键连接而成,39KD组份由24.5KD和18KD两亚基通过二硫键连接而成,23KD球蛋白组份遇热沉淀。     

不同预处理对小鼠粪样菌群高通量测序分析结果的影响

应用高通量测序技术比较不同预处理对小鼠粪样菌群结构的影响,以期为后续相关研究提供参考依据。采集昆明小鼠新鲜粪样,分为原始粪样组、生理盐水处理组和PBS处理组,提取粪样DNA,采用Illumina MiSeq平台进行测序对3组样本的16S rRNA V3~V4区基因文库进行生物信息学分析。结果显示,3组样本拥有共同的OTUs 188个,不同预处理对粪样微生物多样性和丰度产生影响,生理盐水处理组、PBS处理组和原始粪样组分别检出14、11、12个门,3组样本共有门11个;分别检出24、21、21个纲,3组样本共有纲20个;分别检出62、55、59个科,3组样本共有科26个;分别检出147、126、137个属,3组样本共有属117个。总体来看,生理盐水处理组微生物多样性和丰度相对最高,原始粪样组次之,PBS处理组最低。粪样经生理盐水处理后,能在一定程度上提高肠道菌群检测的准确性。     

Terpenoids from Euphorbia helioscopia and Their Cytotoxic Activities against H1975 Cells

Three previously undescribed diterpenoids, helioscopnoids A–C, and eight known compounds were isolated from the whole plants of Euphorbia helioscopia. Their structures were established by extensive analysis of spectra and data comparison with previous literatures. Among them, compound 4 was identified as 24,24-dimethoxy-25,26,27-trinoreuphan-3β-ol with revised configurations of C-13, C-14, and C-17 (13R*, 14R*, 17R*). Cytotoxicity assays revealed that all compounds exhibited varying levels of cytotoxicity against H1975 cells, with compound 9 displaying the most potent activity, as indicated by cell viability rates of 18.13 % and 20.76 % at concentrations of 20 μM and 5 μM, respectively. This study expands the understanding of E. helioscopia terpenoids’ structural diversity and biological activities, contributing to the exploration of potential therapeutic applications.     

Changing synaptic specificities in the nervous system of Caenorhabditis elegans: Differentiation of the DD motoneurons

During postembryonic development, the DD motoneurons in the nematode Caenorhabditis elegans completely reorganize their pattern of synapses. Ablation of a pair of embryonic precursors results in the absence of this entire class of motoneurons. In their absence animals exhibit two developmentally distinct locomotory defects. The transition period from one defect to the other is correlated with the synaptic reorganization of the DD mns. Mutations in a gene (unc-123) have been isolated that exhibit locomotory defects similar to those of the ablated adult animals. Genetic and cellular analyses of one of these alleles suggest that the unc-123 gene product may be involved in the reestablishment of functional synapses in these neurons. © 1993 John Wiley & Sons, Inc.